Sheet-glass downflow apparatus



Patented Nov. 20, 1928-.

UNITED STATES 1,692,615 PATENT ori-uca.

JAMES C. BLAIR,0F TOLEDO, OHIO, ASSIGNOB TO THE LIBBEY-OWENS SHEET GLASS COMPANY, OF TOLEDO, OHI10, A CORPORATION 0F OHIO. i

SHEET-GLASS DOWNLOW APPARATUS.

Application tiled February 24, 1925. Serial No. 11,099.

This invention relates to improvements in the art of producing sheet glass, and more particularly to an improved method and aparatus for forming the sheet by `flowing and drawing the molten glass through an elongated orifice'in the bottom of the container.

According to this invention the slot or lthe orifice through which the molten glass flows downwardly is substantially wider than the thickness of the glass sheet which is to be formed. The molten stream flowing downwardly through this slot is cooled or chilled b a pair of water-cooled or air-cooled heatagsorbing members arranged closely adjacent the sides of tlie emerging stream, the glass thus being converted' into a plastic mass which is stretched downwardly into sheet forni by its own weight assisted by suitable drawing and guiding means which engage the formed sheet some distance below the orilice. Arranged directly below the slot and at the Y ends thereof are preferably rotatable knu'rled rolls which engage the edges of the sheet being formed to assist in forming the same and to.form an edge thereon to hold the sheet to vwidth after it has been formed, and to also assist in more rapidly forming the sheet, thus increasing the possible rate of draw. Immediately below the coolers the formed sheet passes into a closed annealing chamber wherein the sheet is tempered and annealed. This chamber is heated principally by the heat transmitted from the glass sheet itself.

In the drawings wherein like numerals are employed to designate like parts throughout the saine:

Fig. 1 is a fragmentary sectional perspective view illustrating the apparatus in operation,

Fig. 2 is a fragmentary plan view of the sheet-termin mechanism.

Fig. 3 isa ottoin plan view of thedevice,

Fig. 4 isa transverse vvertical section through the sheet-forming orifice, and

Fig. 5 is a longitudinal sectional view through one of the sheet-edge-forming devices.

The molten glass 1 is producedin the tank or furnace 2 from which it flows into the relatively shallow tank or flowing chamber 3. The main purpose of the shallow tank 3 is to reduce the head of glass above `the flowing slot hereinafter described, and to facilitate the temperature control of the body of refined downwardly the formed sheet Arefractory clay with a non-corrosive allo molten lass which supplies the sheet-forining mec anism.

In the bottom of the tank 3 is arranged the forming member or block 4 constructed of a suitable refractory material. At its upper edges this block has supporting flanges 5 which rest in suitable recesses in the surrounding blocks of the furnace.. Extending vertically through the central portion of the block is the elongated longitudinal slot or ori- -lice through which the molten glass flows to form the sheet. The shape and size of the orifice or slot can be changed to Vsuit the de` sire, although in Fig. 2, I have shown the slot fi as having a relatively large end' 7 which is adapted to permit a suliicient flow of glass along the border portions of the sheet being drawn to form an edge thereon. The inner faces 8 of the slot 6 are adapted to curve and merge into the horizontal plane defined by the bottom of the pot 3. It is' to be understood that'the refractory member 4 can be formed from a non-corrosive alloy which ma be internally heated or cooled to control the temperature thereof. Furthermore, the shape into the form of a sheet 10 by the weight of assisted by the pairs of driven supporting and guiding rolls 11 positioned a considerable distance below the said slot.- The frictional contact of the glass flowing through the slot in the refractor member 4 will reduce the temperature of t e glass passing into the sheet to a point where, when it leaves the end of the slot, it will be viscous enouoh to withstand its own weight when actedb upon by the heat-absorbing shields 9. The discharge end of the slot may be lined in those instances where it is formed vfrom a 12 which will revent the formation of and other surdice defects in the sheet. y To assist in the formation of the edge of. the sheet and to facilitate a more rapid drawing or flowingga pair of rotatable preferably knurled rolls 13 are provided, one on each los 'side of the sheet and at both edges thereof.

Each roll 13 is supported on a hollow shaft ing through the slotted orifice 14 which contains a'conduit 15 having a con-l siderably smaller diameter.

A cooling medium such as water or air may be circulated through the pipe 15, inner bore 16 of the roll 13, and may be ermitted to pass out between the pi e 15 an. will a sorb sufficient heat from the edges of the sheet being formed toA create afairly stiff edge which will maintain the sheet to width after it has been formed. In addition, the knurled rolls will control the amount of glass passing into the border portions. 4

The glass sheet 10 which is drawn downwardly from the plastic mass of lass emergtween the coolers '9 passes almost immediatel into the closed annealing chamber 18 which entirely surrounds the sheet and drawing mechanism for a considerable distance below the coolingl zone. This chamber 18 is of comparatively small cross-section and is heated almost entirely by the heat drawn out from the glass sheet 10. As the sheet passes downwardly through the gradually cooling atmosphere in this chamber 18, it will be annealed, and afterv assing out the lower end it may be divided into sheet sections in any approved manner. The chamber also revents access to the forining glass sheet of 'rt and disturbing air currents.

With this type of apparatus a sheet of glass may easily be formed by lowin a mass ot' molten glass through an elongate orifice formed in the bottom of the container holding the glass. The rictional resistance or contact caused by the refractory member and the inherent tendency of plastic glass to adhere to such substances will permit a uniform thickness of sheet to be flowed or drawn through the slot. The sheet may be permitted to flow of its own accord, or it may be drawn more rapidly than the natural flow` through the slot, this dependin upon the thickness of sheet desired. The s eet is held to width by the edge-forming means 13 which shaft 14. The knurled rolls` :.eeaexe create'a relatively tough edge on the sheet e same to width capable of maintaining th after it has been lformed. It is to be understoodthat the shape of the knurled rolls 13 can be modified to 'suit the desires of the particular user.

It is to be understood that the form of the invention herewith shown and described 1s to be taken as the preferred embodiment of the same, and that various changes in the shape, size and-arr angement of parts may be resorted to without departing from the spirit of the invention subjoined claims.

aims: 1. The method of forming sheet glass, consisting in iiowin glass downward y from a container throng a passage having enlarged relatively wide openings at its opposite ends, and providing means below the relatively wide openings to control the iiow of glass into the border portions of the sheet being formed.

2. In an apparatus for producing sheet glass, the combination of a container for molten glass provided with a submerged elonted discharge outlet wider at each end t an at its center, and means below the outlet and adjacent the end portions thereof for engaging the edge rtions of the sheet to hold the same to wi th.

3. In an apparatusl for pioducing sheet glass, the combination of a container for molten lass provided with a submerged elongated scharge outlet wider at each end than at its center, means below the outlet and adjacent the end portionsthereof for engaging the edge portions of the sheet to hold the same to width, and means intermediate the outlet and said last named means for absorbing heat from the body portieri of the sheet.-

Signed at Toledo, and State of Ohio, ary, 1925.

JAMES C. BLAIR.

or the scope of theI 

